​We all use the electrical appliances like fans, lights, a/c etc in our homes, offices, and the public places as per our convenience. It is summer time in India and May-June are too hot to live without air coolers or the air conditioners.

We often use terms like power, energy, and electricity etc in our day to day language but have you ever think that how these terms are related, how these are measured and what are their actual meanings? In this section, we learn the few basic concepts dealing with the consumption and the measurement of the electricity and the power in our daily lives.

What is electricity?

Electricity is the rate of flow of the charge, electrons, per unit time. If I say that 1000 electrons are flowing from one point to another point in 1 second. Then the electric current would be total charge per unit time. I can write in the following equation:

I (current) = Total charge flowing / time

Charge in one electron = \(1.6 * 10^{-19}\) coulombsTime = 1 secondThe charge in 1000 electrons would be \(1000 * 1.6 * 10^{-19}\) coulombsThe current would be = Total charge/time = \(1.6 * 10^{-16}\)AmperesWe think that electrons are consumed when we run our electrical appliances but actually we provide energy to the electrons to run our electrical appliances and we pay for this energy.

Understanding the power

What specification of the CFL or the bulb do you provide to the shopkeeper, whenever it gets fused? Yes, you tell him to provide the bulb or the CFL in terms of wattage.Power is nothing but the rate of doing work.Let us understand with a simple example, your office is on the 5th floor (10 meters from the ground) and you are standing on the ground floor. You weigh 60 Kgf, use the staircase to reach the 5th floor and you do this activity in 2 minutes or 120 seconds. What is your rate of doing the work?

Work done by you = 60 kgf x 10 meters = 600 kgf-m or Joules

Power will be 600 /120 = 5 watt

Another day, you are late, use the staircase and run to your cabin in 60 seconds.

Work done will be the same = 600 kgf-m or Joules

Your power consumption or the rate of doing work, in this case is 600 / 60 = 10 watt

It means that 10 watt of the muscular power is used at any moment of time between when you just started running and just about to reach the 5th floor.You can see in the above example that although the work done is the same in both the cases but the power gets doubled in the case ii, indicating that the double amount of the muscular power is used at every moment of time when you started running using the staircase.Similarly, a 20-watt led bulb will draw 20 watts of the electric power any moment of time whenever the switch is on. More is the power; the higher is the rate of doing work. On the above basis, you can say that a 25-watt bulb will be brighter than the 20 watts bulb.

Watt-hours and the Kilowatt-hours

These are generally the measurement of the energy, indicating the amount of the total energy consumed over a period of time. For example, I say that the 20 watts bulb is used for 5 hours in a day, means that 20 watts x 5 hours = 100 watt- hours of the energy is consumed in this period of time. Similarly, in 1 hour the 20 watts bulb will use 20 x 1 watt- hours of the electricity.These terms are generally used to indicate the consumption of the electrical energy on the larger scale like household consumption in a month. Let us suppose, you run the following electrical appliances:

The monthly energy consumed is 52800 watt-hours or 52.8 KW-hours. We count 1 KW-hour as 1 unit and the electricity department charges according to the units consumed. The units consumed in your case are 52.8 units. Let’s say that 1 unit costs Rs. 5, then the total monthly bill would be 52.8 x 5 = Rs. 264 + the fixed charges.

Conclusion

​The electricity is nothing but the flow of the charge per unit time. The power plants provide the energy to the electrons to flow from one point to another to run our electrical appliances. The rate of doing work is called as the power. The energy is time independent while the power is time dependent and any two cases can have same energy but different powers.Now, have you got the feel of the electricity or not?Well, I will discuss something more simple and important in the next article. Keep sharing with your friends to create energy awareness.